Relationships between parent and child executive functioning were examined, controlling for the critical potential confound of IQ, in a family study involving 434 children (130 girls and 304 boys) and 376 parents from 204 community recruited families at high risk for the development of substance use disorder. Structural equation modeling found evidence of separate executive functioning and intelligence (IQ) latent variables. Mother's and father's executive functioning were associated with child's executive functioning (beta = 0.34 for father-child and 0.51 for mother-child), independently of parental IQ, which as expected was associated with child's IQ (beta = 0.52 for father-child and 0.54 for mother-child). Familial correlations also showed a significant relationship of executive functioning between parents and offspring. These findings clarify that key elements of the executive functioning construct are reliably differentiable from IQ, and are transmitted in families. This work supports the utility of the construct of executive function in further study of the mechanisms and etiology of externalizing psychopathologies. (Contains 5 figures and 4 tables.)